Fluid control valves are typically comprised of a valve assembly and an actuator which applies a motive force to a plunger rod or other coupling device of the valve assembly to open and close the valve. The most common actuator used with fluid control valves is a solenoid device. A solenoid actuator generally consists of an electrical coil which when energized with an electrical potential, produces an electromagnetic field that is utilized to apply a motive force to a magnetized work element such as a plunger.
Many fluid control valves have been previously disclosed. For example, U.S. Pat. No. 5,979,482, the disclosure of which is incorporated herein by reference in its entirety, discloses a solenoid actuated pilot valve assembly specially adapted for use in irrigation systems. The pilot valve comprises a solenoid device having a cylindrical housing enclosing an electrical coil. The electrical coil surrounds a ferrous plunger which is operatively coupled to a valve sealing cap of the pilot valve. When the coil of the solenoid is energized, the plunger retracts thereby allowing the valve sealing cap to retract from its valve seat and opening the pilot valve.
The solenoid actuated fluid control valve suffers from several drawbacks. For one, a solenoid is relatively heavy and bulky because it requires an electrical coil and a magnetizable plunger element. In addition, solenoid devices have fast actuation times which can result in excessive water hammer.
Accordingly, there is a need for an actuator and fluid control valve which overcome the drawbacks of previous designs.